EP3422554A1 - Reversible ac/dc converter with thyristors - Google Patents

Abstract

The invention relates to a converter comprising: two transistors (S1, S2) between two terminals (11, 12) of a DC voltage (Vdc); an inductive element (L1) connecting a first midpoint (13) of the series connection of the two transistors to a first terminal (15) of an alternating voltage (Vac); a first thyristor (SCR1) and a second thyristor (SCR2) in series between the DC voltage terminals, a second midpoint (17) of the series connection of the first thyristor and the second thyristor being connected to a second terminal (16 ) the AC voltage, an anode of the first thyristor and a cathode of the second thyristor being connected to said second midpoint; and a third thyristor (SCR3) and a fourth thyristor (SCR4) in series between the DC voltage terminals, a cathode of the third thyristor and an anode of the first thyristor being connected to said second midpoint.

Description

Field

The present application relates generally to electronic circuits and, more particularly, switching converters known totem pole output, or cascode midpoint.

Presentation of the prior art

Switching converters are used in many applications and many types of converters are known.

Among the AC-DC converters, many bridge architecture architectures and other bridgeless architectures are known, based on the switching of two transistors (usually MOS) mounted in the mid-point cascode (totem pole).

These converters are generally used for their efficiency in correcting the Power Factor Corrector (PFC).

summary

There is a need to improve totem pole converters.

One embodiment proposes a reversible totem pole converter architecture.

One embodiment proposes a solution compatible with a limiting of the inrush current.

• un premier transistor à effet de champ et un deuxième transistor à effet de champ en série entre une première borne et une deuxième borne destinées à une tension continue ;
• un élément inductif reliant un premier point milieu de l'association en série des deux transistors à une première borne destinée à une tension alternative ;
• un premier thyristor et un deuxième thyristor en série entre les bornes de tension continue, un deuxième point milieu de l'association en série du premier thyristor et du deuxième thyristor étant relié à une deuxième borne destinée à la tension alternative, une anode du premier thyristor et une cathode du deuxième thyristor étant reliées audit deuxième point milieu ; et
• un troisième thyristor et un quatrième thyristor en série entre les bornes de tension continue, une cathode du troisième thyristor et une anode du premier thyristor étant reliées audit deuxième point milieu.

Thus, an embodiment provides a reversible AC-DC converter comprising:

• a first field effect transistor and a second field effect transistor in series between a first terminal and a second terminal for DC voltage;
• an inductive element connecting a first midpoint of the series connection of the two transistors to a first terminal for an alternating voltage;
• a first thyristor and a second thyristor in series between the DC voltage terminals, a second midpoint of the series connection of the first thyristor and the second thyristor being connected to a second terminal for the AC voltage, an anode of the first thyristor and a cathode of the second thyristor being connected to said second midpoint; and
• a third thyristor and a fourth thyristor in series between the DC voltage terminals, a cathode of the third thyristor and an anode of the first thyristor being connected to said second midpoint.

• une première diode est en parallèle avec le premier transistor (S1), anode côté premier point milieu ; et
• une deuxième diode est en parallèle avec le deuxième transistor, cathode côté premier point milieu.

According to one embodiment:

• a first diode is in parallel with the first transistor (S1), anode side first midpoint; and
• a second diode is in parallel with the second transistor, cathode side first midpoint.

According to one embodiment, each diode is defined by the intrinsic drain-source diode of the transistor in question.

According to one embodiment, the thyristors are cathode gate.

• le premier thyristor et le quatrième thyristor sont à gâchette de cathode ; et
• le deuxième thyristor et le troisième thyristor sont à gâchette d'anode.

According to one embodiment:

• the first thyristor and the fourth thyristor are trigger cathode; and
• the second thyristor and the third thyristor are anode trigger.

• le premier thyristor et le quatrième thyristor sont à gâchette d'anode ; et
• le deuxième thyristor et le troisième thyristor sont à gâchette de cathode.

According to one embodiment:

• the first thyristor and the fourth thyristor are anode trigger; and
• the second thyristor and the third thyristor are trigger cathode.

• le deuxième thyristor est rendu passant de façon continue pendant des alternances d'un premier signe de la tension alternative ;
• le premier thyristor est rendu passant de façon continue pendant des alternances d'un deuxième signe de la tension alternative ;
• le deuxième transistor est commandé de façon impulsionnelle pendant les alternances du premier signe ; et
• le premier transistor est commandé de façon impulsionnelle pendant les alternances du deuxième signe.

According to one embodiment, in an AC-DC conversion mode:

• the second thyristor is turned on continuously during alternations of a first sign of the alternating voltage;
• the first thyristor is turned on continuously during alternations of a second sign of the alternating voltage;
• the second transistor is pulsed during the alternations of the first sign; and
• the first transistor is impulse-controlled during the alternations of the second sign.

According to one embodiment, the first diode serves as a free-wheel diode.

• le quatrième thyristor est rendu passant de façon continue pendant des alternances d'un premier signe de la tension alternative ;
• le troisième thyristor est rendu passant de façon continue pendant des alternances d'un deuxième signe de la tension alternative ;
• le premier transistor est commandé de façon impulsionnelle pendant les alternances du premier signe ; et
• le deuxième transistor est commandé de façon impulsionnelle pendant les alternances du deuxième signe.

According to one embodiment, in a continuous-to-alternative conversion mode:

• the fourth thyristor is turned on continuously during alternations of a first sign of the alternating voltage;
• the third thyristor is turned on continuously during alternations of a second sign of the alternating voltage;
• the first transistor is pulse-controlled during the alternations of the first sign; and
• the second transistor is impulse-controlled during the alternations of the second sign.

According to one embodiment, the second diode serves as a free-wheel diode.

Brief description of the drawings

• la figure 1 est un schéma électrique d'un exemple usuel de convertisseur totem pole alternatif-continu ;
• la figure 2 représente, de façon schématique et partielle, en partie sous forme de blocs, un mode de réalisation d'un convertisseur totem pole réversible ;
• les figures 3A, 3B, 3C, 3D, 3E, 3F, 3G et 3H illustrent, sous forme de chronogrammes, le fonctionnement du convertisseur de la figure 2 en mode de conversion alternatif-continu ;
• les figures 4A, 4B, 4C, 4D, 4E, 4F, 4G et 4H illustrent, sous forme de chronogrammes, le fonctionnement du convertisseur de la figure 2 en mode de conversion continu-alternatif ;
• la figure 5 représente, de façon schématique et simplifiée, un mode de réalisation d'un circuit de génération de tensions continues de circuits de commande d'un convertisseur totem pole réversible, adapté au mode de réalisation de la figure 2 ;
• la figure 6 représente, de façon schématique et partiellement sous forme de blocs, un autre mode de réalisation d'un convertisseur totem pole réversible ;
• la figure 7 représente, de façon schématique et partiellement sous forme de blocs, un autre mode de réalisation d'un convertisseur totem pole réversible ;
• la figure 8 représente, de façon schématique et partiellement sous forme de blocs, un mode de réalisation d'un circuit de génération de tensions continues de circuits de commande des convertisseurs des figures 6 et 7 ;
• la figure 9 représente, de façon schématique et partiellement sous forme de blocs, un autre mode de réalisation d'un convertisseur totem pole réversible ; et
• la figure 10 représente, de façon schématique et partiellement sous forme de blocs, un mode de réalisation d'un circuit de génération de tensions continues d'alimentation de circuits de commande du convertisseur de la figure 9.

These and other features and advantages will be discussed in detail in the following description of modes of particular embodiment made in a non-limiting manner in relation to the attached figures among which:

• the figure 1 is a circuit diagram of a common example of a totem pole alternator-DC converter;
• the figure 2 represents, schematically and partially, partly in the form of blocks, an embodiment of a reversible totem pole converter;
• the FIGS. 3A, 3B, 3C, 3D, 3E, 3F, 3G and 3H illustrate, in the form of chronograms, the operation of the converter of the figure 2 in alternative-continuous conversion mode;
• the FIGS. 4A, 4B, 4C, 4D, 4E, 4F, 4G and 4H illustrate, in the form of chronograms, the operation of the converter of the figure 2 in continuous-AC conversion mode;
• the figure 5 represents, schematically and simplified, an embodiment of a circuit for generating DC voltages of control circuits of a reversible totem pole converter, adapted to the embodiment of the figure 2 ;
• the figure 6 shows, schematically and partially in the form of blocks, another embodiment of a reversible totem pole converter;
• the figure 7 shows, schematically and partially in the form of blocks, another embodiment of a reversible totem pole converter;
• the figure 8 represents schematically and partially in the form of blocks, an embodiment of a circuit for generating DC voltages of control circuits of the converters of Figures 6 and 7 ;
• the figure 9 shows, schematically and partially in the form of blocks, another embodiment of a reversible totem pole converter; and
• the figure 10 represents, schematically and partially in the form of blocks, an embodiment of a circuit for generating continuous control circuit power supply voltages of the converter of the figure 9 .

detailed description

The same elements have been designated with the same references in the various figures. In particular, the structural and / or functional elements common to the different embodiments may have the same references and may have identical structural, dimensional and material properties.

For the sake of clarity, only the steps and elements useful for understanding the embodiments that will be described have been shown and will be detailed. In particular, the final application of the converter has not been detailed, the described embodiments being compatible with the usual applications of AC-DC, DC or reversible converters.

Unless otherwise specified, when reference is made to two elements connected to one another, this means directly connected without any intermediate element other than conductors, and when reference is made to two interconnected elements, it means that these two elements can be directly connected (connected) or connected through one or more other elements.

In the following description, the terms "approximately", "substantially", and "of the order of" mean within 10%, preferably within 5%.

The figure 1 is a circuit diagram of a common example of a totem pole, AC-DC converter.

A totem pole converter is based on the use of two MOS transistors (here N channel) S1 and S2, connected in series between two terminals 11 and 12 for supplying a DC voltage Vdc. The drain of the transistor S1 is on the terminal side 11 and the source of the transistor S2 is on the terminal side 12. A storage element C1 (capacitor or battery for example) of the continuous energy connects the terminals 11 and 12, the terminal 11 being arbitrarily , the positive terminal of the voltage Vdc. The midpoint 13 between the two transistors S1 and S2 is connected, via a inductive element L1 in series with a circuit 14 for limiting the inrush current and losses in steady state, at a first terminal 15 for applying an alternating voltage Vac. The circuit 14 is, for example, a resistor R (positive temperature coefficient PTC or negative NTC) in parallel with a switch K. The resistor R limits the inrush current at startup and the switch K bypasses the resistance in steady state to limit the resistive losses once the voltage equilibrium is reached. A second terminal 16 for applying the AC voltage Vac is connected to the mid-point 17 of a series connection of two diodes D3 and D4 connected between the terminals 11 and 12. The anodes of the diodes D3 and D4 are respectively point-side 17 and terminal 12 side.

In practice, the terminals 15 and 16 correspond to connection terminals to the electrical distribution network and an input filter 18 (FILTER), or mains filter, is interposed between on the one hand the terminal 15 and the circuit 14 and, on the other hand, the terminal 16 and the point 17. An element 19 for measuring the alternating current is interposed between the filter 18 and the point 17. The information representative of the current, measured by the element 19, is exploited by a control circuit (CTRL) of the conduction periods of transistors S1 and S2. The circuit 20 receives other information such as, for example, information representative of the voltage Vdc, information representative of the energy requirements of the load connected to the terminals 11 and 12, etc. The circuit 20 provides control signals to circuits (DRIVER) 21 and 22 for generating gate control signals of respective transistors S1 and S2. In figure 1 the intrinsic source-drain diodes D1 and D2 of the transistors S1 and S2 have also been represented. The transistors S1 and S2 are controlled in pulse width modulation as a function of the needs of the load connected to the terminals 11 and 12. The frequency of the pulses is generally fixed and is clearly higher (ratio of at least 100, for example of a few kHz to a few hundred kHz) at the voltage frequency Vac (generally less than 100 Hz, typically 50 Hz or 60 Hz for the electricity distribution network).

The operation of the totem pole converter of the figure 1 is the next. For simplicity, it does not take into account the presence of the filter 18 but it is of course traversed by the current from the terminals 15 and 16 and to these terminals.

During the positive half-cycles of the voltage Vac, the transistor S2 is controlled in pulse width modulation to be periodically closed (on) and the transistor S1 remains permanently open (blocked). Moreover, the source-drain diode D2 of the transistor S2 is reverse-biased while the source-drain diode D1 of the transistor S1 is directly biased and serves as a free-wheel diode. During the closing pulses of the transistor S2, the inductance L1 accumulates energy. The flow of current is effected, from terminal 15, via inductance L1, transistor S2 and diode D4 to terminal 16. The continuous load connected to terminals 11 and 12 is supplied by the energy stored in the energy storage element C1 (capacitor or battery). At each opening of the transistor S2, the energy stored in the inductor L1 is transferred to the continuous load. The flow of the current then takes place from the inductor L1, via the diode D1 of the transistor S1 to the positive terminal 11, then from the negative terminal 12, via the diode D4 to the terminal 16 to loop back on the inductor L1. In some cases, the diode D1 is a diode in parallel on the transistor S1.

During the negative half-waves of the voltage Vac, the transistor S1 is controlled in pulse width modulation to be periodically closed (on) and the transistor S2 remains permanently open (blocked). Furthermore, the source-drain diode D1 of the transistor S1 is reverse biased whereas the source-drain diode D2 of the transistor S2 is directly biased and serves as a freewheeling diode. During the closing pulses of the transistor S1, the inductance L1 accumulates energy. The flow of current is effected, from the terminal 16, via the diode D3, the transistor S1 and the inductance L1 to the terminal 15. The continuous load connected to the terminals 11 and 12 is fed by the energy stored in the energy storage element C1. At each opening of the transistor S2, the energy stored in the inductor L1 is transferred to the continuous load. The flow of the current is then effected from the inductance L1, via the terminals 15 and 16, the diode D3, to the positive terminal 11, then the negative terminal 12, via the diode D2 to the inductor L1.

The inrush current limiting circuit 14 is used before each closing pulse of one of the transistors S1 and S2, in particular when moving away from the voltage zero of the voltage Vac. Indeed, the voltage across the transistor S1 or S2 when closed is all the more important that we are close to the middle of the corresponding alternation, which, without limitation circuit, would cause a current spike. The opening of the switch K, in a pulse manner, before each beginning of the closing pulse of the transistors S1 and S2 so that the resistor R limits the charging current of the capacitor C1, avoids these peaks of current, in particular towards the middle of each alternation.

The converter of the figure 1 is unidirectional, that is, it can only operate in AC-DC converter (rectifier or rectifier mode). In some applications, it is desired to have a reversible converter, that is to say able to operate also as a DC-AC converter. This serves, for example, to reinject energy into the electrical distribution network or to supply an engine from a battery. The converter must then be able to operate inverter (inverter).

The embodiments described provide for taking advantage of the advantages of a totem pole architecture and its efficiency to produce a reversible converter.

An example of application of a reversible converter is to allow, with the same converter, both to feed a load from the distribution network electrical and inject energy on the network when the load does not consume.

Another example of application of a reversible converter is to allow, with the same converter, both to supply a motor (transfer of electrical-mechanical energy) from a battery and recharge the battery (transfer mechanical-electrical energy) from the motor rotation.

One might think to use MOS transistors instead of diodes D3 and D4 to make the structure bidirectional. However, the need to limit the inrush current makes this solution very restrictive in terms of control of the MOS transistors and the size and reliability of the steady-state loss limitation circuit. The circuit 14 for limiting the inrush current is also essential.

The figure 2 represents, schematically and partially, partly in the form of blocks, an embodiment of a reversible totem pole converter.

There is a totem pole structure of two field effect transistors S1 and S2, for example MOS transistors (here N channel), connected in series between two terminals 11 and 12 of a DC voltage Vdc. The drain of the transistor S1 is on the terminal side 11 and the source of the transistor S2 is on the terminal side 12. A storage element C1 (capacitor or battery for example) of the continuous energy connects the terminals 11 and 12, the terminal 11 being arbitrarily , the positive terminal of the voltage Vdc.

The mid-point 13 between the two transistors S1 and S2 is connected, via an inductive element L1, to the first terminal 15 of an alternating voltage Vac. According to the embodiments described, provision is made to replace the diodes D3 and D4 of the figure 1 by four thyristors SCR1, SCR2, SCR3, SCR4. Two thyristors SCR1 and SCR2 are connected in series between the terminals 11 and 12, the anodes of thyristors SCR1 and SCR2 being directed towards the terminal 12. Two thyristors SCR3 and SCR4 are connected in series between the terminals 11 and 12, the anodes of the thyristors SCR3 and SCR4 being directed to terminal 11. The point The medium 17 of the series associations of thyristors SCR1 and SCR2 and thyristors SCR3 and SCR4 is common and is connected to a second terminal 16 of the alternating voltage Vac. In the example of the figure 2 the thyristors are all trigger cathode.

As will be seen later, thanks to the proposed solution, a current limiting circuit (14, figure 1 ) is not necessary.

The terminals 15 and 16 correspond, for example, to terminals for connection to the electrical distribution network or to the terminals of a motor, etc., and an input filter 18, or mains filter, is preferably interposed between on the one hand the terminal 15 and the node 13 and, secondly, the terminal 16 and the point 17. An element 19 for measuring the alternating current is interposed between the filter 18 and the point 17. The information representative of the current, measured by the element 19 is operated by a control circuit 20 (CTRL) of the conduction periods of the transistors S1 and S2. The circuit 20 receives other information such as, for example, information representative of the voltage Vdc, representative information, in rectifier mode, the needs of the continuous load connected to the terminals 11 and 12, etc. The circuit 20 supplies control signals to circuits (DRIVER) 21 and 22 for generating control signals of the gates gS1 and gS2 of the respective transistors S1 and S2. The circuit 20 also provides, directly or indirectly, control signals to the gSCR1, gSCR2, gSCR3 and gSCR4 gates of the SCR1, SCR2, SCR3 and SCR4 thyristors. In figure 2 the intrinsic source-drain diodes D1 and D2 of the transistors S1 and S2 have also been represented. Alternatively, diodes D1 and D2 may be additional components. According to another variant, the transistor S1 or S2 is turned on during the periods when the current must flow in the diode D1, respectively D2. This makes it possible to reduce the conduction losses with respect to a current flow in the intrinsic diode D1 or D2. Transistors S1 and S2 are controlled in pulse width modulation. Pulse frequency is usually fixed and is significantly higher (ratio of at least 100, for example from a few kHz to a few hundred kHz) at the frequency of the voltage Vac (generally less than 100 Hz, typically 50 Hz or 60 Hz for the electricity distribution network). The converter does not raise or lower the voltage in one direction or another. We are only concerned here about the alternative-continuous conversion and vice versa. Where appropriate, other conversion and control systems are present upstream or downstream to achieve a decrease or increase in the values of voltages Vd and Vdc.

The use of thyristors in both directions of conduction in a totem pole architecture seems at first sight unnecessary because of the presence of transistors S1 and S2. However, as can be seen from the embodiments below, the use of four thyristors instead of two diodes makes it possible not only to avoid the inrush current limiting circuit, but also to make the converter reversible with particularly simple control.

The FIGS. 3A, 3B, 3C, 3D, 3E, 3F, 3G and 3H illustrate, in the form of chronograms, the operation of the converter of the figure 2 in AC-DC conversion mode during a period of AC voltage Vac.

The figure 3A represents an example of the shape of the voltage Vac between the terminals 15 and 16 (line voltage or motor). The figure 3B represents a corresponding example of the pace of the current Iac or line or motor current. The figure 3C represents an example of a corresponding trend of the voltage Vdc between terminals 11 and 12 (battery voltage or capacitor C1). The 3D figure represents a corresponding example of the shape of the current Idc side DC voltage. The figure 3E represents an example of closing periods of the SCR2 thyristor. The figure 3F represents an example of a corresponding pace of the gate voltage gS2 of the transistor S2. The figure 3G represents an example of closing periods of the SCR1 thyristor. The figure 3H represents an example corresponding pace of the gate voltage gS1 of the transistor S1.

It is placed in steady state, that is to say that it is considered that the capacitor C1 is at the load level required by the application. The start-up operation is similar but the voltage Vdc gradually increases over several alternations until it reaches its nominal level set by the application. To simplify the explanations, we neglect the presence of the filter 18 in what follows.

In AC-DC conversion mode, the SCR3 and SCR4 thyristors are not used and remain locked.

The SCR2 thyristor is turned on during the positive halfwaves of the voltage Vac while the SCR1 thyristor is turned on during the negative alternations of the AC voltage. However, unlike the D3 and D4 diodes of the classical case of figure 1 , the conduction of thyristors SCR1 and SCR2 does not depend on the conduction periods of transistors S1 and S2, but is forced during the maximum of the possible duration of the positive and negative halfwaves. This duration covers at least the entire duration of the control pulse train of the transistors S1 and S2, and is set by the half-period of the AC voltage. Thus, the closing of the transistor S1 or S2 (according to the alternation of the voltage Vac) is effected while the voltage at its terminals is approximately zero. The control of transistors S1 and S2 is not modified by the described embodiments. It will be noted that the SCR1 or SCR2 thyristor blocks at the end of alternation when the current flowing through it vanishes (becomes lower than its holding current).

During the positive half-cycles of the voltage Vac, the transistor S2 is controlled in pulse width modulation to be periodically closed (on) and the transistor S1 remains permanently open (blocked). Moreover, the source-drain diode D2 of the transistor S2 is reverse-biased while the source-drain diode D1 of the transistor S1 is directly biased and serves as a free-wheel diode. During the impulses of closing the transistor S2, the inductor L1 accumulates energy. The flow of current is effected, from terminal 15, via inductance L1, transistor S2 and thyristor SCR2 to terminal 16. The continuous load connected to terminals 11 and 12 is supplied by the energy stored in the energy storage element C1 (capacitor or battery). At each opening of the transistor S2, the energy stored in the inductor L1 is transferred to the continuous load. The flow of the current then takes place from the inductance L1, via the diode D1 of the transistor S1 to the positive terminal 11, then from the negative terminal 12, via the SCR2 thyristor to the terminal 16 to loop back on the inductor L1.

During the negative half-waves of the voltage Vac, the transistor S1 is controlled in pulse width modulation to be periodically closed (on) and the transistor S2 remains permanently open (blocked). Furthermore, the source-drain diode D1 of the transistor S1 is reverse biased whereas the source-drain diode D2 of the transistor S2 is directly biased and serves as a freewheeling diode. During the closing pulses of the transistor S1, the inductance L1 accumulates energy. The flow of current is effected, from terminal 16, via thyristor SCR1, transistor S1 and inductance L1 to terminal 15. The continuous load connected to terminals 11 and 12 is supplied by the energy stored in the energy storage element C1. At each opening of the transistor S2, the energy stored in the inductor L1 is transferred to the continuous load. The flow of current is then effected from the inductance L1, via the terminals 15 and 16, the SCR1 thyristor, to the positive terminal 11, then the negative terminal 12, via the diode D2 to the inductor L1.

The use of four thyristors has another advantage which is to allow operation in inverter, that is to say in continuous-AC conversion.

The FIGS. 4A, 4B, 4C, 4D, 4E, 4F, 4G and 4H illustrate, in the form of chronograms, the operation of the converter of the figure 2 in DC-AC conversion mode during a period of AC voltage Vac.

The Figure 4A represents an example of the shape of the voltage Vac between the terminals 15 and 16 (line voltage or motor). The Figure 4B represents a corresponding example of the pace of the current Iac or line or motor current. The figure 4C represents an example of a corresponding trend of the voltage Vdc between terminals 11 and 12 (battery voltage or capacitor C1). The figure 4D represents a corresponding example of the shape of the current Idc side DC voltage. The figure 4E represents an example of closing periods of the SCR4 thyristor. The figure 4F represents an example of a corresponding pace of the gate voltage gS2 of the transistor S2. The figure 4G represents an example of closing periods of the SCR3 thyristor. The Figure 4H represents an example of a corresponding shape of the gate voltage gS1 of the transistor S1.

In UPS mode, the question of the steady state of voltage Vdc does not arise. Indeed, it is here to transfer energy from the continuous source (charged battery for example) to the alternative load.

To operate in the inverter, that is to say for example to reinject energy on the electrical distribution network or to supply a motor, the direction of flow of the current in the converter must be reversed with respect to the case of the AC-DC converter. continued. So, with the same sign conventions, the Idc current is all the time negative. Moreover, the sign of the current Iac is inverted with respect to the sign of the voltage Vac, that is to say that it is negative during the positive and positive half-waves during the negative half-waves.

As for the rectifier mode, the SCR4 thyristor is continuously turned on during the positive alternations of the AC voltage Vac while the SCR3 thyristor is turned on continuously during the negative half-waves of the AC voltage Vac. However, side transistors S1 and S2, unlike the rectifier mode, the transistor S1 is controlled during the positive half cycles and the transistor S2 is controlled during the negative half-waves of the voltage Vac. The transistors S1 and S2 are always pulse-wise controlled, preferably in pulse width modulation if the alternating load is likely to vary (for example in the case of a motor).

In continuous-AC conversion mode, the SCR1 and SCR2 thyristors are not used and remain locked.

During the positive half-cycles of the voltage Vac, the transistor S1 is controlled in pulse width modulation to be periodically closed (on) and the transistor S2 remains permanently open (blocked). Furthermore, the source-drain diode D1 of the transistor S1 is reverse biased whereas the source-drain diode D2 of the transistor S2 is directly biased and serves as a freewheeling diode. During the closing pulses of the transistor S1, the inductance L1 accumulates energy. The flow of the current is effected, from the terminal 11, via the transistor S1 and the inductance L1 to the terminal 15, then the terminal 16, via the SCR4 thyristor to the terminal 12. At each opening of the transistor S1, the energy stored in the inductance L1 is transferred to the AC network (or the motor). The flow of the current is then from the inductor L1 to the terminal 15, then the terminal 16, via the SCR4 thyristor and the diode D2 to the inductance L1.

During the negative half-waves of the voltage Vac, the transistor S2 is controlled in pulse width modulation to be periodically closed (on) and the transistor S1 remains permanently open (blocked). Moreover, the source-drain diode D2 of the transistor S2 is reverse-biased while the source-drain diode D1 of the transistor S1 is directly biased and serves as a free-wheel diode. During the closing pulses of the transistor S2, the inductance L1 accumulates energy. The current flows from terminal 11 via thyristor SCR3 to terminal 16 and from terminal 15 via the inductance L1 and the transistor S2 to the terminal 12. At each opening of the transistor S2, the energy stored in the inductance L1 is transferred to the AC network. The flow of the current then takes place from the inductor L1, via the diode D1, the thyristor SCR3 to the terminal 16, loops through the terminal 15 in the inductance L1.

Compared to the rectifier mode, one ensures at each end of alternation, stopping the control pulses of the transistors S1 and S2 sufficiently early to ensure that the current Iac is zero at the end of the alternation.

The applications particularly targeted are applications in which the voltages Vac and Vdc have amplitudes greater than 100 volts. However, the control signals of transistors S1 and S2 and thyristors SCR1 to SCR4 have amplitudes ranging from a few volts to 10-20 volts. Therefore, there must be circuits for generating these control signals having appropriate voltage references.

The following figures show the connections and supply potentials required for the control signals of the transistors and triacs in different embodiments.

The figure 5 represents, schematically and simplified, an embodiment of a circuit 4 (DC POWER SUPPLY) for generating DC voltages of control circuits of a reversible totem pole converter, adapted to the embodiment of the figure 2 .

In the realization of the figure 2 , the circuit 4 must generate four DC voltages V1, V2, V3 and V4 of different amplitudes, respectively intended for the SCR1 thyristor, the SCR2 and SCR3 thyristors, the control circuit 21 of the transistor S1, and common to the control circuit of the transistor S2, the SCR4 thyristor and the circuit 20 (for example, a microcontroller).

On the transistor side S2, its source being the ground GND (potential of the terminal 12), the reference potential of its gate control signal gS2 can also be the ground GND. The circuit 22 is powered by a positive voltage V4, for example of the order of 15 volts, which can be used to generate a voltage of a few volts supplying the circuit 20. Similarly, the injection of a gate current into the thyristor S4 whose cathode is GND ground can be carried out from this voltage of a few volts referenced GND ground.

Transistor side S1, the voltage of terminal 11 is too high to allow a command gS1 referenced GND ground. Preferably, provision is made to reference a DC supply voltage, for example a given value chosen between a few volts and fifteen volts, from the circuit 21 to the node 13. As the node 13 corresponds to the source of the transistor S1, This ensures a positive gate-source voltage whatever the potential of the node 13 (which evolves with the voltage Vac). For this purpose, a voltage V3 is generated, for example 15 volts (referenced GND ground). The application of this voltage to supply the circuit 21 requires a voltage reference change. An embodiment will be described in relation to the figure 6 .

SCR1 thyristor side, one must generate a voltage V1 which can not be referenced GND ground either. Preferably, this voltage is generated with a reference to the potential of the terminal 11. An example of a circuit for applying the voltage V1 to the gate of the SCR1 thyristor for injecting a trigger current will be deduced later from the description of the figure 6 . An example of a circuit for generating this voltage V1 can be deduced from the presentation of the figure 8 .

SCR2 and SCR3 thyristors side, we must also inject a trigger current with a voltage reference different from the GND mass. The voltage V2 is preferably also referenced to the potential of point 17. Here again, an example of a circuit for generating this voltage V2 and its application to the triggers of the SCR2 and SCR3 thyristors will be deduced subsequently from the description of FIG. the figure 6 .

The figure 6 represents, schematically and partially in the form of blocks, another embodiment of a reversible totem pole converter.

Compared to the diagram of the figure 2 the SCR2 and SCR3 thyristors are anode gate thyristors. The rest of the editing is not modified. The consequence is that the voltage references of the SCR2 and SCR3 thyristor gates must be modified in order to extract a trigger current in order to prime them. The figure 6 also illustrates a circuit for generating the voltage V3 (supply of the circuit 21) from the voltage V4 (15VDC) and illustrates the supply of the circuit 22 by the voltage V4 (15VDC).

Thus, as indicated, the source of the transistor S2 being the ground GND (potential of the terminal 12), the reference potential of its gate control signal gS2 can also be the ground GND. The circuit 22 is therefore, for example, powered by a positive voltage 15VDC (terminal 51), of 15 volts, referenced GND ground and receives a low voltage digital signal CTRLS2 (a few volts, for example 3-5 volts) of the circuit 20 (for example, a microcontroller).

Transistor side S1, the voltage of terminal 11 is too high to allow a command gS1 referenced GND ground. In the example of the figure 6 , it is expected to reference the supply voltage, for example 15 volts, of the circuit 21 to the node 13. As the node 13 corresponds to the source of the transistor S1, thus ensures a positive gate-source voltage regardless of the potential of the node 13 (which evolves with the voltage Vac). A 15VDC potential of 15 volts (referenced GND ground) is applied (terminal 51) on the anode of a diode D5 whose cathode is connected to a terminal 52 for applying the positive supply potential of the circuit 21. A terminal 53 for applying the reference potential of the circuit 21 is connected to the node 13. A capacitor C2 connects the cathode of the diode D5 to the node 13 to adapt the reference of the voltage of 15 volts supplying the circuit 21. Because of the change of voltage reference, a low voltage control signal CTRLS1, supplied by the circuit 20, is applied via an optocoupler 54 (Opto) whose conduction terminals (the emitter and the collector of the bipolar output phototransistor) are respectively connected to the terminal 52 and to a control input terminal of the circuit 21. The signal CTRLS1 is applied to the control terminal of the optocoupler (the anode of its photodiode) being referenced GND ground.

SCR1 and SCR3 thyristor cores, the conduction terminals (phototransistor emitter and collector) of the transistor of an optocoupler 55 (Opto) are connected to an electrode of a capacitor C3 defining a terminal 56 for applying a positive potential VDC_SCR1 / 3 of a continuous supply (for example, of the order of 15 volts) insulated (floating) referenced to a floating mass GND_SCR1 / 3, and the gate of the SCR1 thyristor to inject a trigger current. The floating ground terminal GND_SCR1 / 3 of this isolated supply is also connected, by a resistor R1, to the gate (anode) of the SCR3 thyristor, to extract a gate current. A low voltage control signal CNTRL_SCR1 / 3, supplied by the circuit 20, is applied to the control terminal of the optocoupler 55 (the anode of its photodiode) by being referenced GND ground. When the signal CNTRL_SCR1 / 3 is active, the transistor of the optocoupler 55 is on and a current flows from the terminal 56, in the gate of the SCR1 thyristor (which starts), towards the terminal 11, towards the anode of the SCR3 thyristor and is extracted from its trigger (SCR3 SCR3 thyristor therefore starts) to return to the floating GND_SCR1 / 3.

On the SCR2 and SCR4 thyristor cores, the conduction terminals (emitter and collector of the phototransistor) of the transistor of an optocoupler 57 (Opto) are connected to the anode gate of the SCR2 thyristor for picking up a gate current and a d-electrode. a capacitor C4 defining a terminal 58 for applying a GND_SCR2 / 4 floating mass of a continuous supply (for example, of the order of 15 volts) isolated referenced to this floating mass. A positive potential VDC_SCR2 / 4 of this insulated power supply is applied, by a resistor R2, to the gate (cathode) of the SCR4 thyristor to inject a trigger current therein. A low voltage control signal CNTRL_SCR2 / 4, provided by the circuit 20, is applied to the control terminal of the optocoupler 55 (the anode of its photodiode) being referenced GND ground. When the signal CNTRL_SCR2 / 4 is active, the transistor of the optocoupler 55 is on and a current flows from the potential VDC_SCR2 / 4, in the gate of thyristor SCR4 (which starts), towards the terminal 12, towards the SCR2 thyristor anode and is extracted from its trigger (the SCR2 SCR2 starts) to return to the terminal 58.

The figure 7 represents, schematically and partially in the form of blocks, another embodiment of a reversible totem pole converter.

Compared to the diagram of the figure 2 the SCR1 and SCR4 thyristors are anode gate and the SCR2 and SCR3 thyristors are cathode gate. The consequence is on the side of the application voltage references of the thyristor control signals, the rest of the circuit not being modified. Compared to the figure 6 control assemblies (optocoupler 55, capacitor C3, resistor R1, application of relative potentials VDC_SCR1 / 3 and GND_SCR1 / 3, optocoupler 57, capacitor C4, resistor R2, application of relative potentials VDC_SCR2 / 4 and GND_SCR2 / 4) are identical . The difference is that, on thyristor SCR1 and SCR3 side, it is the gate of the SCR1 thyristor (instead of that of the SCR3 thyristor) which is connected to the resistor R1 and it is the gate of the SCR3 thyristor (instead of that of the SCR3 thyristor). thyristor SCR1) which is connected to the optocoupler 55. SCR2 and SCR4 thyristor side, it is the gate of the SCR2 thyristor (instead of that of the SCR4 thyristor) which is connected to the resistor R2 and is the trigger of the thyristor SCR4 (instead of the terminals 11 and 12 respectively).

The figure 8 represents schematically and partially in the form of blocks, an embodiment of a circuit for generating DC voltages of control circuits of the converters of Figures 6 and 7 .

This figure illustrates an example of a potential generation setup VDC_SCR1 / 3, GND_SCR1 / 3, VDC_SCR2 / 4, GND_SCR2 / 4, 15VDC and 3.3VDC (microcontroller power supply 20) from the AC voltage Vac.

A transformer 8 with three secondary windings 81, 82 and 83 is used. A primary winding 84 of the transformer 8 is connected between the terminal 15 by a rectifying diode D8 (for example only the positive half-waves are used for the generation of the power supplies) and a terminal of a switching converter 85 (CONV), for example an integrated circuit known under the trade name VIPER, whose other terminal is connected to terminal 16 ( Figures 5 to 7 ).

The first secondary winding 81 of the transformer 8 provides the floating voltage VDC_SCR1 / 3-GND_SCR1 / 3. For this, a first terminal of the winding 81 defines the potential GND_SCR1 / 3 and is connected to the resistor R1. A second terminal of the winding 81 is connected to the input (anode) of a rectifying element D81 (for example, a diode). The output (cathode) of the rectifying element D8 defines the potential VDC_SCR1 / 3 and is connected to the terminal 56.

The second secondary winding 82 of the transformer 8 provides the floating voltage VDC_SCR2 / 4-GND_SCR2 / 4. For this, a first terminal of the winding 82 defines the potential GND_SCR2 / 4 and is connected, in the embodiment of the Figures 6 and 7 at terminal 58. A second terminal of winding 82 is connected at the input (anode) of a rectifying element D82 (for example, a diode). The output (cathode) of the rectifying element D82 defines the potential VDC_SCR2 / 4 and is connected, via a linear regulator 86 (REG), in the embodiment of the Figures 6 and 7 , at resistance R2. A capacitor C82 connects the cathode of diode D83 to floating GND_SCR2 / 4.

The third secondary winding 83 of the transformer 8 supplies the voltage 15VDC-GND. For this, a first terminal of the winding 83 defines the GND potential and is connected to the terminal 12. A second terminal of the winding 83 is connected at the input (anode) of a rectifying element D83 (for example, a diode). The output (cathode) of the rectifying element D83 defines the potential 15VDC and is connected to the terminal 51. A capacitor C83 connects the cathode of the diode D83 to the ground GND.

The amplitudes of the voltages VDC_SCR1 / 3-GND_SCR1 / 3, VDC_SCR2 / 4-GND_SCR2 / 4 and 15VDC-GND depend on the transformation ratios of the windings 81, 82 and 83 with respect to the winding 84.

In the example shown, the voltage 15VDC is used to generate the low voltage 3.3VDC (for example, 3.3 volts) referenced GND ground for the circuit or microcontroller 20. For this, we use, for example, a linear regulator 87 (REG). A capacitor C87 connects the output of the converter to the terminal 12 (ground GND).

The figure 9 represents, schematically and partially in block form, a variant of the embodiment of the figure 6 wherein the control signal CNTRL_SCR2 / 4, GND ground reference, is applied to the cathode gate of the SCR4 thyristor through the resistor R4 and the anode gate of the SCR2 thyristor via a charge pump circuit 71 (Pump Charge) powered by the voltage 15VDC. The rest of the editing is not changed in relation to the figure 6 .

The figure 10 represents, schematically and partially in the form of blocks, an embodiment of a circuit for generating continuous control circuit power supply voltages of the converter of the figure 9 .

This figure illustrates an example of a generation of generation potential VDC_SCR1 / 3, GND_SCR1 / 3 and 15VDC from the AC voltage Vac.

A transformer 9 with two secondary windings 92 and 93 is used. A primary winding 91 of the transformer is connected between the terminal 15 and a terminal of a switching converter 95 (CONV), for example an integrated circuit known under the trade name VIPER , whose other terminal is connected to terminal 16.

A first secondary winding 92 of the transformer 9 provides the voltage VDC_SCR1 / 3-GND__SCR1 / 3. For this, a first terminal of the winding 92 defines the potential GND_SCR1 / 3 and is connected to the resistor R1 ( figure 9 ). A second terminal of the winding 92 is connected at the input (anode) of a rectifying element D92 (for example, a diode) and a capacitor C92 connects the two terminals of the winding 92. The output (cathode) of the element D92 defines the potential VDC_SCR1 / 3 and is connected to the terminal 56 ( figure 9 ).

A second secondary winding 93 of the transformer 9 supplies the voltage 15VDC-GND. For this, a first terminal of the winding 93 defines the GND potential and is connected to the terminal 12. A second terminal of the winding 93 is connected at the input (anode) of a rectifying element D93 (for example, a diode). A capacitor C93 connects the two terminals of the winding 93. The output (cathode) of the rectifier element D93 defines the potential 15VDC and is connected to the terminal 51.

The amplitudes of the voltages VDC_SCR1 / 3-GND_SCR1 / 3 and 15VDC-GND depend on the transformation ratios of the windings 92 and 93 with respect to the winding 94.

Here also, the voltage 15VDC-GND can be used to generate the low voltage (for example, 3.3 volts) referenced GND ground for the circuit or microcontroller 20. For this, one uses, for example, a linear regulator 97 (REG).

An advantage of the embodiments described is that the totem pole converter thus produced is particularly efficient. In particular, it eliminates the need for a current limiting circuit, while obtaining a reversible converter.

Particular embodiments have been described. Various variations and modifications will be apparent to those skilled in the art. In particular, the choice of mounting among those of figures 2 , 6 , 7 or 9 depends on the application and the circuit used to generate the control voltages. Indeed, the circuits of figures 8 and 10 are just examples and we can alternatively use voltages present in the rest of the application. In addition, the practical implementation of the embodiments and the dimensioning of the components is within the abilities of those skilled in the art from the functional description given above.

Claims (10)

Reversible AC-DC converter, comprising: a first field effect transistor (S1) and a second field effect transistor (S2) in series between a first terminal (11) and a second terminal (12) for a DC voltage (Vdc); an inductive element (L1) connecting a first midpoint (13) of the series connection of the two transistors to a first terminal (15) for an alternating voltage (Vac); a first thyristor (SCR1) and a second thyristor (SCR2) in series between the DC voltage terminals, a second midpoint (17) of the series connection of the first thyristor and the second thyristor being connected to a second terminal (16 ) for the alternating voltage, an anode of the first thyristor and a cathode of the second thyristor being connected to said second midpoint; and a third thyristor (SCR3) and a fourth thyristor (SCR4) in series between the DC voltage terminals, a cathode of the third thyristor and an anode of the first thyristor being connected to said second midpoint. Converter according to claim 1, wherein: a first diode (D1) is in parallel with the first transistor (S1), anode side first midpoint (13); and a second diode (D2) is in parallel with the second transistor (S2), cathode side first midpoint (13). Converter according to claim 2, wherein each diode (D1, D2) is defined by the intrinsic drain-source diode of the transistor (S1, S2) concerned. Converter according to any one of claims 1 to 3, wherein the thyristors (SCR1, SCR2, SCR3, SCR4) are cathode gate. Converter according to any one of claims 1 to 3, wherein: the first thyristor (SCR1) and the fourth thyristor (SCR4) are cathode gate; and the second thyristor (SCR2) and the third thyristor (SCR3) are anode gate. Converter according to any one of claims 1 to 3, wherein: the first thyristor (SCR1) and the fourth thyristor (SCR4) are anode gate; and the second thyristor (SCR2) and the third thyristor (SCR3) are cathode gate. A method of controlling a converter according to any one of claims 1 to 6, wherein in an AC-DC conversion mode: the second thyristor (SCR2) is turned on continuously during alternations of a first sign of the alternating voltage (Vac); the first thyristor (SCR1) is turned on continuously during alternations of a second sign of the alternating voltage; the second transistor (S2) is pulsed during the alternations of the first sign; and the first transistor (S1) is pulse-controlled during the alternations of the second sign. A method according to claim 7, in its connection to claim 2 or 3, wherein the first diode (D1) serves as a freewheeling diode. A method of controlling a converter according to any one of claims 1 to 6, wherein in a DC-to-AC conversion mode: the fourth thyristor (SCR4) is turned on continuously during alternations of a first sign of the alternating voltage (Vac); the third thyristor (SCR3) is turned on continuously during alternations of a second sign of the alternating voltage; the first transistor (S1) is pulse-controlled during the alternations of the first sign; and the second transistor (S2) is impulse-controlled during the alternations of the second sign. A method according to claim 9, in its connection to claim 2 or 3, wherein the second diode (D2) serves as a freewheeling diode.

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